Integrated gasification combined cycle (“IGCC”) power plants are capable of generating energy from various types of hydrocarbon feed stocks in a relatively clean and efficient manner. IGCC technology may convert the hydrocarbon feed stock into a gaseous mixture of carbon monoxide and hydrogen, i.e., a synthetic gas or a syngas, by reaction with oxygen and steam in a gasifier. These gases then may be cleaned, processed, and utilized as a fuel in a gas turbine engine in a conventional combined cycle power plant and the like.
In processing the flow of hot, dirty syngas leaving the gasifier, the flow first may be cooled. For example, a convective syngas cooler may be used downstream of the gasifier. The convective syngas cooler has the advantage of being able to circulate a cooling medium to exchange heat with the hot syngas such that the cooling medium may be used to provide useful work in a steam turbine and the like. The solids entrained in the flow of the dirty syngas, however, have a tendency to plug the convective syngas cooler such that efficiency may suffer and downtime may be required. Another alternative to cool the syngas is to use a direct quench chamber instead of a convective syngas cooler. The use of the direct quench cooler avoids the plugging issue and thus may increase overall plant availability. The useful work produced by the cooling medium in the convective syngas cooler, however, is lost such that overall plant performance may be decreased.
There is thus a desire for an improved gasifier and cooling system for use in an IGCC power plant and the like. Preferably such an improved gasifier cooling system may adequately cool the flow of the hot, dirty syngas without efficiency loses and downtime caused by solids plugging a convective syngas cooler and while retaining overall plant performance and efficiency.